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Nanomaterials with low-dimensional morphology display unique properties in catalysis and related fields, which are highly dependent on the structure and aspect ratio. Thus, accurate identification of the structure and morphology is the basis to correlate to the performance. However, the widely adopted techniques such as XRD is incapable to precise identify the aspect ratio of low-dimensional nanomaterials, not even to quantify the morphological uniformity with statistical deviation value. Herein, ZnO nanorod and nanosheet featured with one- and two-dimensional morphology were selected as model materials, which were prepared by the hydrothermal method and statistically characterized by transmission electron microscopy (TEM). The results indicate that ZnO nanorods and nanosheets display rod-like and orthohexagnal morphology, which mainly encapsulated with {100} and {001} planes, respectively. The 7.36 ± 0.20 and 0.39 ± 0.02 aspect ratio (c/a) of ZnO nanorods and nanosheets could be obtained through the integration of the (100) and (002) diffraction rings in selected area electron diffraction (SAED). TEM combining with the SAED is favorable compare with XRD, which not only provides more accurate aspect ratio results with standard deviation values but also requires very small amounts of sample. This work is supposed to provide a convenient and accurate method for the characterization of nanomaterials with low-dimensional morphology through TEM.

A previous study demonstrated that infection of rat oligodendrocytes by mouse hepatitis virus (MHV) resulted in apoptosis, which is caspase dependent (Y. Liu, Y. Cai, and X. Zhang, J. Virol. 77: 11952-11963, 2003). Here we determined the involvement of the mitochondrial pathway in MHV-induced oligodendrocyte apoptosis. We found that caspase-9 activity was 12-fold higher in virus-infected cells than in mock-infected cells at 24 h postinfection (p.i.). Pretreatment of cells with a caspase-9 inhibitor completely blocked caspase-9 activation and partially inhibited the apoptosis mediated by MHV infection. Analyses of cytochrome c release further revealed an activation of the mitochondrial apoptotic pathway. Stable overexpression of the two antiapoptotic proteins Bcl-2 and Bcl-xL significantly, though only partially, blocked apoptosis, suggesting that activation of the mitochondrial pathway is partially responsible for the apoptosis. To identify upstream signals, we determined caspase-8 activity, cleavage of Bid, and expression of Bax and Bad by Western blotting. We found a drastic increase in caspase-8 activity and cleavage of Bid at 24 h p.i. in virus-infected cells, suggesting that Bid may serve as a messenger to relay the signals from caspase-8 to mitochondria. However, treatment with a caspase-8 inhibitor only slightly blocked cytochrome c release from the mitochondria. Furthermore, we found that Bax but not Bad was significantly increased at 12 h p.i. in cells infected with both live and UV-inactivated viruses and that Bax activation was partially blocked by treatment with the caspase-8 inhibitor. These results thus establish the involvement of the mitochondrial pathway in MHV-induced oligodendrocyte apoptosis.

It has recently been shown that cell entry of mouse hepatitis virus type 2 (MHV-2) is mediated through endocytosis (Z. Qiu et al., J. Virol. 80 :5768-5776, 2006). However, the molecular mechanism underlying MHV-2 entry is not known. Here we employed multiple chemical and molecular approaches to determine the molecular pathways for MHV-2 entry. Our results showed that MHV-2 gene expression and infectivity were significantly inhibited when cells were treated with chemical and physiologic blockers of the clathrin-mediated pathway, such as chlorpromazine and hypertonic sucrose medium. Furthermore, viral gene expression was significantly inhibited when cells were transfected with a small interfering RNA specific to the clathrin heavy chain. However, these treatments did not affect the infectivity and gene expression of MHV-A59, demonstrating the specificity of the inhibitions. In addition, overexpression of a dominant-negative mutant of caveolin 1 did not have any effect on MHV-2 infection, while it significantly blocked the caveolin-dependent uptake of cholera toxin subunit B. These results demonstrate that MHV-2 utilizes the clathrin- but not caveolin-mediated endocytic pathway for entry. Interestingly, when the cells transiently overexpressed a dominant-negative form (DIII) of Eps15, which is thought to be an essential component of the clathrin pathway, viral gene expression and infectivity were unaffected, although DIII expression blocked transferrin uptake and vesicular stomatitis virus infection, which are dependent on clathrin-mediated endocytosis. Thus, MHV-2 entry is mediated through clathrin-dependent but Eps15-independent endocytosis.

respiratory, digestive, neurological, and immune-mediated diseases in human and animals. The outbreak of the severe acute respiratory syndrome (SARS) in 2003 was caused by SARS-CoV, which is most closely related to group II CoV, especially the bovine CoV (BCoV). Although the exact origin of SARS-CoV remains to be identified, the fact that similar SARS-CoV has been repeatedly isolated in wild animals, including civet cat, raccoon dog, and badges, strongly suggests that SARS-CoV originates from animals. It was postulated that SARS-CoV is a zoonotic pathogen. Ironically, the zoonotic nature of CoV had been documented long before the outbreak of SARS. In 1994, Zhang et al., reported the isolation of a human enteric CoV (HECoV) from a 6-year old child with

One of the hirudin variants HV3 was efficiently expressed in Escherichia coli using the l -asparaginase II signal sequence and the product was secreted into the culture medium. For the secretory manufacture of HV3, the l -asparaginase II signal sequence containing a single Nhe I restriction site at its 3 ′ end was designed using the degenerate codons and PCR-amplified from E. coli chromosomal DNA. The synthetic HV3 coding sequence was fused to the signal sequence in-frame by its 5 ′ Nhe I restriction site. The above signal-HV3 fusion gene was inserted into an expression vector pTA, which was derived from pkk223-3 such that its expression was under the control of the tac promotor. The resulting HV3 secretion expression vector pTASH thus constructed was introduced into an E. coli host cell AS1.357 with high l -asparaginase II producing level. After inducing with IPTG, the expression product was efficiently secreted into the culture medium and shake-flask culturing gave a yield of approximately 5×10 5 ATU/L (∼ 60 mg / L ). The secreted HV3 was easily purified from culture supernatant using ultrafiltration, ion-exchange column chromatography, and FPLC reverse-phase chromatography. The purified rHV3 from the culture supernatant had the expected N-terminal amino sequence and strong antithrombin activity, suggesting that the signal sequence was completely removed and the product was processed accurately during the secretion process.